R: Need info on AGPS

[Harald Welte]

On Thu, Jan 25, 2007 at 05:12:09PM +0100, Marcus Bauer wrote:
> On Thu, 2007-01-25 at 16:24 +0100, Harald Welte wrote:
> 
> > > 3. A-GPS involves additional data traffic and thus (potential) additional
> > > costs. Does it use a normal GSM/GPRS IP-based data transfer? does it use
> > > some out-of-band GSM/GPRS control messages? or does it get data from
> > > broadcasts in the local cell (e.g. GSM cell-broadcast)?
> > 
> > AFAIK: GPRS.  so its up to you whether you want that extra traffic (and
> > cost, unless you're flat) or not.
> 
> The Global Locate docs state TCP/IP as one possible way. So via
> USB-network or BT should be possible too.

What do you think do we run on top of usbnet and bluetooth BNEP ? The
answer is: TCP/IP ;)

So anything that uses TCP/IP and can be attached to the phone will be
able to connect the AGPS server[s].

> You need it only once for the first fix. It is ~2KB for all satellites
> and valid for 2-4 hours. Precomputed for a week maybe 1MB.

One thing that we should look into is to have something like an RSS Feed
of that data, which can be downloaded everytime we have a cheap
(bluetooth, usbnet) IP connectivity. Then cache all that data locally.

-- 
- Harald Welte <laforge at openmoko.org>          	        http://openmoko.org/
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